if you have a high concentration of adenosine what's that going to make you want to do that's going to bind to certain receptors and we know when those receptors get bound to you fall asleep Bingo caffeine will competitively bind to those receptors therefore that's why caffeine stops you from feeling like you want to go to sleep right so we have a very clear relationship between exercise fuel in fact if you look at the literature there's a pretty clear relationship between the more caloric expenditure in different sports and the higher amount of hours needed for sleep